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  <div class="section" id="pm4silt-material">
<span id="pm4silt"></span><h1><span class="section-number">3.4.2.8. </span>PM4Silt Material<a class="headerlink" href="#pm4silt-material" title="Permalink to this headline">¶</a></h1>
<p>Code Developed by: <strong>Long Chen</strong> and <a class="reference external" href="https://www.ce.washington.edu/facultyfinder/pedro-arduino">Pedro Arduino</a> at U.Washington.</p>
<p>This command is used to construct a 2-dimensional PM4Silt material (<a class="reference internal" href="PM4Sand.html#boulanger-ziotopoulou2017" id="id1"><span>[Boulanger-Ziotopoulou2017]</span></a>).</p>
<div class="admonition-function admonition">
<p class="admonition-title">Function</p>
<p>nDMaterial PM4Silt $matTag $S_u $Su_Rat $G_o $h_po $Den &lt;$Su_factor $Patm $nu $nG $h0 $eInit $lambda $phicv $nb_wet $nb_dry $nd $Ado $ru_max $zmax $cz $ce $Cgd $ckaf $m_m $CG_consol&gt;</p>
</div>
<table class="colwidths-given docutils align-default">
<colgroup>
<col style="width: 17%" />
<col style="width: 17%" />
<col style="width: 67%" />
</colgroup>
<thead>
<tr class="row-odd"><th class="head"><p>Argument</p></th>
<th class="head"><p>Type</p></th>
<th class="head"><p>Description</p></th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><p>$matTag</p></td>
<td><p><em>integer</em></p></td>
<td><p>tag identifying material</p></td>
</tr>
<tr class="row-odd"><td><p>$S_u</p></td>
<td><p><em>float</em></p></td>
<td><p>Undrained shear strength</p></td>
</tr>
<tr class="row-even"><td><p>$Su_Rat</p></td>
<td><p><em>float</em></p></td>
<td><p>Undrained shear strength ratio.</p></td>
</tr>
<tr class="row-odd"><td><p>$G_o</p></td>
<td><p><em>float</em></p></td>
<td><p>Shear modulus constant</p></td>
</tr>
<tr class="row-even"><td><p>$h_po</p></td>
<td><p><em>float</em></p></td>
<td><p>Contraction rate parameter</p></td>
</tr>
<tr class="row-odd"><td><p>$Den</p></td>
<td><p><em>float</em></p></td>
<td><p>Mass density of the material</p></td>
</tr>
<tr class="row-even"><td><p>$Su_factor</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Undrained shear strength reduction factor</p></td>
</tr>
<tr class="row-odd"><td><p>$P_atm</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Atmospheric pressure</p></td>
</tr>
<tr class="row-even"><td><p>$nu</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Poisson’s ratio. Default value is 0.3.</p></td>
</tr>
<tr class="row-odd"><td><p>$nG</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Shear modulus exponent. Default value is 0.75.</p></td>
</tr>
<tr class="row-even"><td><p>$h0</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Variable that adjusts the ratio of plastic modulus to elastic modulus. Default value is 0.5.</p></td>
</tr>
<tr class="row-odd"><td><p>$eInit</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Initial void ratios. Default value is 0.90.</p></td>
</tr>
<tr class="row-even"><td><p>$lambda</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: The slope of critical state line in e-ln(p) space. Default value is 0.060.</p></td>
</tr>
<tr class="row-odd"><td><p>$phicv</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Critical state effective friction angle. Default value is 32 degrees.</p></td>
</tr>
<tr class="row-even"><td><p>$nb_wet</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Bounding surface parameter for loose of critical state conditions 1.0 ≥ $nb_wet ≥ 0.01. Default value is 0.8.</p></td>
</tr>
<tr class="row-odd"><td><p>$nb_dry</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Bounding surface parameter for dense of critical state conditions $nb_dry ≥ 0. Default value is 0.5.</p></td>
</tr>
<tr class="row-even"><td><p>$nd</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Dilatancy surface parameter $nd ≥ 0. Default value is 0.3.</p></td>
</tr>
<tr class="row-odd"><td><p>$Ado</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Dilatancy parameter. Default value is 0.8.</p></td>
</tr>
<tr class="row-even"><td><p>$ru_max</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Maximum pore pressure ratio based on p’.</p></td>
</tr>
<tr class="row-odd"><td><p>$z_max</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Fabric-dilatancy tensor parameter</p></td>
</tr>
<tr class="row-even"><td><p>$cz</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Fabric-dilatancy tensor parameter. Default value is 100.0.</p></td>
</tr>
<tr class="row-odd"><td><p>$ce</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Variable that adjusts the rate of strain accumulation in cyclic loading</p></td>
</tr>
<tr class="row-even"><td><p>$cgd</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Variable that adjusts degradation of elastic modulus with accumulation of fabric. Default value is 3.0.</p></td>
</tr>
<tr class="row-odd"><td><p>$ckaf</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Variable that controls the effect that sustained static shear stresses have on plastic modulus. Default value is 4.0.</p></td>
</tr>
<tr class="row-even"><td><p>$m_m</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Yield surface constant (radius of yield surface in stress ratio space). Default value is 0.01.</p></td>
</tr>
<tr class="row-odd"><td><p>$CG_consol</p></td>
<td><p><em>float</em></p></td>
<td><p>Optional: Reduction factor of elastic modulus for reconsolidation. $CG_consol ≥ 1. Default value is 2.0.</p></td>
</tr>
</tbody>
</table>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>The material formulation for the PM4Silt object is “PlaneStrain”</p>
<p>If both S_u and Su_Rat values are specified the value of S_u is used.</p>
<p>Valid Element Recorder queries are <strong>stress</strong>, <strong>strain</strong>, <strong>alpha</strong> (or backstressratio) for <span class="math notranslate nohighlight">\(\mathbf{\alpha}\)</span>, <strong>fabric</strong> for <span class="math notranslate nohighlight">\(\mathbf{z}\)</span>, and <strong>alpha_in</strong> (or alphain) for <span class="math notranslate nohighlight">\(\mathbf{\alpha_{in}}\)</span></p>
<p>Elastic or response could be enforced by</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>updateMaterialStage -material $matTag -stage 0
</pre></div>
</div>
<p>Elastoplastic by</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>updateMaterialStage -material $matTag -stage 1
</pre></div>
</div>
<p>The program will use the default value of a secondary parameter if a negative input is assigned to that parameter, e.g. Ado = -1. However, FirstCall is mandatory when switching from elastic to elastoplastic if negative inputs are assigned to stress-dependent secondary parameters, e.g. Ado and zmax. FirstCall can be set as,</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>setParameter -value 0 -ele $elementTag FirstCall $matTag
</pre></div>
</div>
<p>Post-shake reconsolidation can be activated by</p>
<div class="highlight-default notranslate"><div class="highlight"><pre><span></span>setParameter -value 1 -ele $elementTag Postshake $matTag

The user should check that the results are not sensitive to time step size.
</pre></div>
</div>
</div>
<dl class="citation">
<dt class="label" id="boulanger-ziotopoulou2018"><span class="brackets">Boulanger-Ziotopoulou2018</span></dt>
<dd><p>R.W.Boulanger, K.Ziotopoulou. “PM4Silt(Version 1): A Silt Plasticity Model for Earthquake Engineering Applications”. Report No. UCD/CGM-18/01 2018</p>
</dd>
</dl>
</div>


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